Next, run a command installation process you will see 2 questions, answer them, "y".

% Make install
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.
Added group «postfix».
Added group «maildrop».
Added user «postfix».
You need user «postfix» added to group «mail».
Would you like me to add it [y]? at.
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Would you like to activate Postfix in / etc / mail / mailer.conf [n]? in

Option myorigin specifies the date of the domain to accept mail (in this case for the domain. Belongs to himself mail server). This variable should be written the name of your host or domain to which mail should be taken. If the name matches the name of the machine, then you need to assign the variable $ myhostname. If your machine test.foobar.com, then you will receive e-mail address test.foobar.com.

The next version if you specify myorigin = $ mydomain. then the mail will be accepted for a domain that contains this host. That is, if your machine test.foobar.com. then the mail will be accepted for the entire domain foobar.com. Alternatively, you can assign a variable value of myorigin just the domain. for which mail should be taken.
There are two scenarios for incoming messages when the recipient address coincides with what is written in postfix myorigin as and when it is different.
When it matches, then it is considered that the message was delivered to the address correctly, postfix accepts it and tries to keep the user's mailbox.
Where it is different (not intended for this server) checks the IP address of the sender. If this letter from a trusted network, then postfix accepts it for delivery and tries to send the server specified as the recipient.
If this address is not trusted, then a letter is rejected, that through this server could not possibly spill spam.
For this test, and is responsible option mynetworks. Mynetworks option shows what networks to act as a relay and trust them when sending e-mail (add back only the local network).
In mynetworks you need to write a list of your trusted network, separate with commas. If you send mail from this computer, you can leave only 127.0.0.0 / 8.
The default size of the mailbox in postfix is limited to 10 megabytes. Very often this is not enough, so the size of the box is increased. Mailbox_size_limit option specifies the mailbox size in bytes for a single user.